1. Field of the Invention
The present invention relates to a portable terminal, and more particularly to a key pad lighting apparatus of a portable terminal.
2. Description of the Related Art
A modem portable terminal is capable of providing, in addition to radio communication functions, various types of content services such as voice communication service, short message transmission, mobile banking, TV, online gaming, VOD (video on demand), etc.
Portable terminals are classified according to their form: a bar-type terminal in which communication circuits and input/output devices, such as a microphone unit and a speaker unit, are installed in a single housing, a flip-type terminal in which a flip cover is installed in the bar-type terminal, and a folder-type terminal which can be opened and closed and in which input/output devices are distributed in the housing. Recently, a slider-type terminal has appeared together with the folder-type terminal to improve the portability, convenience, and aesthetic enhancement.
A portable terminal typically includes a key pad as an input device for inputting information, searching and executing stored information and multimedia files, and selecting a menu. The input devices can also be a touch screen, but most users still control the portable terminal using a key pad having a plurality of keys.
FIG. 1 is a cross-sectional view of a conventional key pad 100 used in a portable terminal. As shown, the conventional key pad 100 includes a printed circuit board 101 in which dome switches 111 are arranged on one surface thereof and a silicone pad 102 on which a plurality of key buttons 123 are arranged. The printed circuit board 101 can be formed of a flexible printed circuit board.
The key buttons 123 are disposed above the dome switches 111, and contact bosses 121 facing the dome switches 111 are formed on the silicone pad 102. If the key buttons 123 are activated by a user, the silicone pad 102 is deformed which in turn causes the contact bosses 121 to activate the dome switches 111. Letters are printed on the key buttons 123 so that a user can input letters to actuate different functions through the key buttons 123. Further, in order to facilitate the use of the key pad at night, the key pad 100 includes a lighting apparatus using light emitting diodes 113, etc. The lighting apparatus including a plurality of light emitting diodes 113 installed on the printed circuit board 101 is provided in the key pad 100. More particularly, the light emitting diodes 113 are provided on both sides of the lower portion of each key button 123. The light generated from the light emitting diodes 113 is diffused through the silicone pad 102 to illuminate the letters printed on the key buttons 123. The lighting apparatuses can be used to illuminate the key pads whenever the key pads are in use.
However, according to the conventional lighting apparatus used in a portable terminal, the assembling process is complicated as the light emitting diodes more than or equal to the number of the key buttons are typically installed on the lower portion of the key buttons. Namely, in the case of a general 3×4 arrangement number key pad, sixteen light emitting diodes are typically provided on both sides of the lower portion of the key buttons. However, in order to accommodate the plurality of light emitting diodes on the printed circuit board, the printed circuit patterns becomes complicated, and additional processes for installing the light emitting diodes are required, thereby increasing the manufacturing cost.